A semiconductor wafer is processed by a semiconductor manufacturer to form various integrated circuits (IC) in different regions of the wafer. The wafer includes a substrate with many patterned material layers thereon that form the discrete devices that make up a circuit. The material layers are patterned by photolithographic steps using photomasks, or simply “masks,” to expose a photoresist layer which may then serve as an etch mask during a patterning etch process. During fabrication various defects may be introduced on or in the wafers or the photomasks used to pattern the wafers. Additionally, when a mask is used in photolithography, defects may be introduced by that use. For example, when subjected to several cleaning processes a mask feature may lose material, altering in shape from the design layout used to create that mask. In some instances, small features such as assist features, which are not intended to be transferred from the mask into the underlying photoresist layer, may detach from the mask after several cleanings. The current approaches to pattern repair have not been entirely satisfactory. Therefore, there is a need of new methods and tools to address such issues.
The drawings may be better understood when viewed in connection with the following detailed description.